Heat-sealable devices for marking textile articles

ABSTRACT

Heat sealable labels or the like and methods and marking articles by means of such labels are described. The label includes a flexible support incorporating a heat-curing filmforming resin system in the presence of alkylol or alkoxy alkyl groups and under acid conditions, and an information-bearing marking printed on said support. Such a label when heat sealed to a textile or other article is wash- and wear-resistant and withstands the various treatments to which the article may be subjected.

United States Patent 1191 Meyer 1 1 Reissued Sept. 2, 1975 1 1HEAT-SEALABLE DEVICES FOR MARKING TEXTILE ARTICLES [75] Inventor: PeterMeyer, London, England [73} Assigncc: Polymark Corporation, Cincinnati,

Ohio

1221 Filed: July 26, 1973 [21] Appl. No.: 382,736

Related US. Patent Documents 161/251, 413; ll7/3.4,14, 15, 60, 68.5, 76P, 122 H, 122 PA, 122 PB, 122 PF, 151, 161

[56] References Cited UNITED STATES PATENTS 2,096,750 10/1937 Lawrence1l7/68.5

2.631.947 3/1953 Kline 117/122 X 2,853,404 9/1958 Weinberg... 117/1222,927,865 3/1960 Lewis et al.... 117/15 X 3,301,696 l/l967 Taube eta]... 117/15 3,359,127 12/1967 Meyer et a1... l 17/3.4 3,616,176 10/1971.lachimowicz. 1l7/3.4 3,684,564 8/1972 Lefrancois 117/3.4

Primary Examiner(]eorge F. Lesmes Assistant ExaminerCharles E. Lipsey [57] ABSTRACT Heat sealable labels or the like and methods and markingarticles by means of such labels are described. The label includes aflexible support incorporating a heat-curing film-forming resin systemin the presence of alkylol or alkoxy alkyl groups and under acidconditions, and an informationbearing marking printed on said support.Such a label when heat sealed to a textile or other article is washandwear-resistant and withstands the various treatments to which thearticle may be subjected.

9 Claims, 1 Drawing Figure Inventor B I MW Mf'jww uww Horne yHEAT-SEALABLE DEVICES FOR MARKING TEXTILE ARTICLES Matter enclosed inheavy brackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

The present invention relates to heat-scalable labels or like markingelements for applying markings or decorative effects to textilearticles, fabrics or other sheet materials or to leather, wood, glass,plastics and so on, and to methods of marking articles, for the purposeof obtaining markings or decorative effects which are substantiallyresistant to Wear, and in the case of textile and like articles areresistant also to repeated cleaning or washing of such articles.

U.S. Pat. No. 3,359,127, commonly owned by the assignee herein,describes methods and means for marking textile articles, including inparticular heat transfers, wherein a temporary support receives a layerof a soluble polyamide in turn carrying a printed marking. This transferis applied under heat and pressure to an article to be marked in thepresence of a curing agent normally consisting of a solid organic acidmixed with the polyamide or it may be ammonium salt of such acid, whichcuring agent promotes cross-linking of the polyamide in the presence ofalkylol or alkoxy-alkyl groups so that a relatively insoluble, inert andwearresistant layer, incorporating the printed marking is bonded to thearticle, after which the temporary support is removed. This arrangementprovides a highly resistant marking on the article which is of apermanent character and can be readily designed so as not to be liableto become degraded throughout, the life of the article even afterrepeated washing and cleaning operations.

The polyamides used may be soluble polyamides or copolyamides which canbe converted into a highly inert and insoluble form by a curing agent inthe presence of a cross-linking agent containing alkylol or alkoxy-alkylgroups, and such cross-linking agent may in some cases be a formaldehyderesin. Other compounds which can be used similarly are dispersions of anacrylic resin capable of being cross-linked at an elevated temperature.

The present invention is directed to a label or like marking devicewhich offers substantially all the advantages of heat transfers producedaccording to the above-noted patent but which can be more economicallyproduced and which has the further important advantage that the timecycle required for applying or bonding the marking to the article to bemarked can in many cases be reduced as compared with the procedureinvolved in the above-noted patent, while, further more, the step ofremoving the temporary support can be avoided which results in a savingof time.

In accordance with the present invention a marking element comprises aflexible support incorporating a heat curing film-forming resin systemin the presence of alkylol or alkoxy alkyl groups and under acidconditions, and an information-bearing marking printed on said support,to provide a marking element which substantially withstands varioustreatments to which the surface may be subjected. More specifically, thesupport may consist of a thin permeable paper impregnated with thefilm-forming resin system, said resin being presented on the surface ofthe label to be bonded to the surface to be marked, there being aprinted marking exposed on the opposite surface of the label.

With such a marking element the support remains bonded to the surfaceand carries a marking or decorative pattern on the exposed surface. Theink used for producing the marking or decorative pattern preferablyemploys a medium consisting of a similar resin to that applied to thesupport so that after the application of heat and pressure the printedlabel, when bonded to a textile article, is not affected by repeatedlaundry or dry (chemical) cleaning treatments to which the article maybe subjected.

One advantage of the present invention is that the support can be formedof a relatively inexpensive material such as paper. By using a thinpermeable paper the presence of such support after bonding the label tothe article is of no disadvantage and provides a backing for the markingor pattern carried by the label. The invention also contemplates the useof a fabric, for example a fine woven cotton fabric, or a thin foil ofplastics.

Since the marking produced on the support is visible at all times,control of the printing or other operations used for producing themarking can be more readily effected than in cases where, as in theabove-noted patent, the printed marking is overlaid by the temporarysupport and is thus not readily available for inspection, while,furthermore, the present invention offers the advantage that printing iseffected in the normal configuration and not in reverse as is oftennecessary when the support is a temporary support which must be removedfrom the article after transfer has been effected.

The fibreor film-forming resin may consist of a solubilised linearpolyamide of the character described in the aforesaid patent and mayconsist of a nylon-type polyamide which has been converted into asoluble form containing alkoxy alkyl groups by treatment with analdehyde such as formaldehyde, as described for example in Britishspecification No. 591,382. Materials of this type are commerciallyavailable under the trademarks Calaton CA and CB (made by LC]. Ltd., andbelieved to be substantially identical to the substance previously soldunder the trademark Maranyl," or BCI Type 800 resins made by BeldingChemical Industries).

Alternatively alcohol-soluble copolyamides may be used in conjunctionwith a cross-linking agent containing alkoxy alkyl groups, and in thiscase the crosslinking agent may be a formaldehyde resin containingalkoxy alkyl groups.

A still further alternative is a cross-linking acrylic resinconveniently in the form of an aqueous dispersion such as that soldunder the trademarks Plextol" (made by Rohm and Haas of Darmstadt) orl-lycar (British Geon, Ltd.).

Polyamide and copolyamide resins of the above types are soluble inalcohols or alcohol/water mixtures, and such resins may be applied inthe form of alcohol or alcohol/water solutions. Acrylic resindispersions may be used in the commercially available form or thedispersion may be thickened by suitable additions if required.

These solutions or dispersions are used as coating or impregnatingagents and are self-curing under acid conditions. Particularly in thecase of polyamide solutions, they may contain an organic acid curingagent or an acid-yielding compound such as an anhydride or an ammoniumor amine salt. Suitable curing agents are preferably those acids orcompounds which are solid at normal temperature. A typical organic acidis citric acid or alternatively ammonium citrate can be used. Such acidsare convenient for the purpose because at room temperature they aresubstantially inactive in promoting cross-linking so that labelsproduced by coating a support with a resin solution and such a solubleorganic acid, have a satisfactory shelf life and are not liable to beaffected by long storage periods; nevertheless curing occurs rapidly andeffectively when the labels are applied to the article to be treated,such application being conveniently at a temperature of the order of 150to 250 C., preferably from 180 to 250 C., and at a specific pressure ofabout to 100 lbs. per square inch.

After coating or impregnating the support and drying the coating at atemperature not exceeding 100C. the desired pattern or marking isprinted on the support and then dried. The printing ink used may consistof a medium which also is a heat curing resin together with suitablepigments and other additions appropriate to a printing medium, and theprinting of the desired design or pattern may be effected by any normalprinting processes, for example letterpress, offset litho, flexographicor gravure processes, or it may be produced by screen printing.

After printing, a continuous coating of the resin mixture may be appliedto form a protective surface on the marking element. Where a continuousouter layer is applied as an overcoating on the printed or decorativemarking there is a higher degree of protection of the marking, and itmay even be possible to use normal types of printing media, for exampleflexographic shellac-based inks.

By using labels or like devices produced according to the presentinvention it is possible to complete the application and bonding of thelabel to the article to be marked in a total period of not more than Ito 7 secondds permitting a very rapid and economical marking sequence.

Several examples of methods of carrying the inven tion into effect willbe described hereinafter as applied by way of example to the productionof the label-like element shown on the accompanying drawing in which asupport 1 consisting of a thin absorbent paper is impregnated with asolution or dispersion of a resin according to one of the followingexamples and after drying may then be coated on one side with a furthercoating of the resin as shown at 2. This coating is on the under side ofthe label which is applied in contact with the surface to be marked.

The opposite face of the support 1 receives a printed pattern or designsuch as is indicated typically at 3 which is applied by a printingprocess in which the medium of the printing ink consists of a resinsolution or dispersion. If desired an overcoating consisting of acontinuous layer of the resin solution or dispersion is applied.

It will be seen that the pattern or design is produced by directprinting and that the design or pattern is visible to the operator whenapplying the label to the article to be marked. Such application iseffected by means of a suitable heatsealing press which bonds the coatedrear surface of the support 1 to the article to be marked and effectscuring and cross-linking of the resin component of the impregnation ofthe support, of the printed marking thereon and of any continuous layerswhich may be present to form a highly inert and resistant marking on thesurface to be marked.

Various solutions and dispersions for use as coating or impregnatingmedia are given below by way of example together with examples ofadditional components which may be present in the coating mixtures andinks, and a number of examples based on the use of certain of thesolutions, dispersions and inks are set out in detail. In all cases theparts are given by weight:

TABLE II.COATING OR IMPREGNATING DISPERSIONS This table comprisescross-linking acrylic resins which may be polymers or copolymers ofalkyl esters of acrylic acid or methacrylic acid comprising N-alkoxyalkyl acrylamide. Typical examples of commercially availableproducts which may be used in accordance with the present invention arethe following:

1. Plextol B5821 2. Plextol Ml7a 3. Hycar 2679 The commerciallyavailable dispersions may be utilised in carrying out the presentinvention in the form received by the makers.

TABLE III.

PRINTING INKS Parts Solution l of Table I l0() Titanium dioxide 15Cadmium yellow 3 (2) Solution 2 of Table I I00 Phthalocyanine blue 10(3) Solution 1 of TableI I00 Carbon black 7 (4) Solution 2 of Table lCadmium red 10 (5) Solution 3 of Table I 100 Carbon black 6 (6) Piextol858a I00 Cadmium red 8 Water 15 Hydroxyethyl cellulose l Nonionicwetting agent 0.3

In preparing this ink the components other than the resin dispersion arepre-dispersed in the water before the resin is added.

Parts Solution 2 of Table I 100 Carbon black 6 Solution 3 of Table I 100Titanium dioxide [5 An ink composition similar to ink No. 6 but in whichthe cadmium red is replaced by 5 parts of carbon black. An inkcomposition similar to ink Nov 6 but in which the resin dispersion isreplaced by Plextol M l7a. An ink composition similar to ink No. 9 butin which the resin dispersion is replaced by Plextol Ml7a. An inkcomposition similar to ink No. 6 but in which the resin dispersion isreplaced by Hycar 2679. An ink composition similar to ink No. 9 but inwhich the resin dispersion is replaced by Hycar 2679.

Parts 25 75 In preparing labels in accordance with the present inventionany of the resins of Tables I or [I may be used, and theinformationbearing marking may be produced by any of the inks of TableIII other than ink No. 14. In many cases it is desirable, but it is notalways essential to utilise coating or impregnating media and printinginks comprising the same resin. Different resins can be used forprinting particularly in those cases where the information-bearingmarking is protected by an additional coating as in Examples III, Vlband VII, or when the ink can be caused to bond strongly to the permanentsupport itself rather than the coating or impregnating resin as in thecase of Examples II and Vla.

In many cases it may be desirable that plasticisers should be present inthe coating or impregnating media and in the printing inks. In the caseof polyamide solutions and inks containing polyamides, that is to say,the coating solutions of Table I and printing inks Nos. 1 to 5, 7 and 8,any of the following plasticisers may be used but it should beunderstood that this list is not exhaustive and that other suitableplasticisers are available and could be used.

TABLE IV.

PLASTICISERS FOR POLYAMIDE MEDIA N-ethyl toluene sulphonamidetris-dipropylene glycol phosphite, polyethylene glycol.

In the case of cross-linking acrylic resins such as the dispersions ofTable I] and printing inks Nos. 6 to 13,

any of the following plasticisers can be used but again this list is notexhaustive.

TABLE V.

PLASTICISERS FOR CROSS-LINKING ACRYLIC RESIN DISPERSIONS dibutylphthalate dioctyl phthalate,

tri-cresyl phosphate.

N-elhyl toluene sulphonamide.

presence of 1% ofa non-ionic wetting agent, for exam ple one of theproducts sold under the trademark Nonex supplied by Union Carbide &Chemical Cor poration.

All the printing inks in Table III including ink No. 14 are suitable foruse in the flexographic or gravure printing processes. Inks Nos. 1 to 13are also suitable for use by the screen printing process and in thiscase the industrial ethanol may be replaced by nbutanol or diacetonealcohol.

The cross-linking agent referred to in solutions 2 and 3 of Table I andin the corresponding printing inks Nos. 4, 5, 7 and 8 comprise compoundsof formaldehydes with for example urea and melamine containing alkoxyalkyl groups which in some cases may be formaldehyde resins. Thesecompounds may be selected from the following table which illustratestypical examples of suitable compounds but is not an exhaustive list ofcrosslinking agents.

TABLE VI.

CROSS-LINKING AGENTS N,N'bis( methoxymethyl )uron,

tri-methoxymethyl melamine,

hexa-methoxymethyl melamine,

tetra-methoxymethyl urea,

urea-formaldehyde precondensate containing methoxymethyl groups melamineformaldehyde precondensatcs containing methoxymethyl groups.

hexa-ethoxymethyl melamine,

urea-formaldehyde precondensates containing ethoxymethyl groups,

melamine-formaldehyde precondensates containing ethoxy-methyl groups.

N,N'-bis(methoxymethyl )metaphenylene diamine,

In preparing the solutions and dispersions based on the compounds andmixtures set out in the foregoing tables the fluid coating orimpregnating media may be prepared by high-speed stirring except wherecommercially available dispersions are used in the form received by themakers. In the preparation of printing inks the pigments may beintroduced by ball milling and additional substances such as the curingagents for example triammonium citrate or citric acid added withstirring. Coating or impregnating mixtures according to Table I or Table[I may be applied to the permanent support in any convenient way as acontinuous coating or by causing a continuous strip of the supportmaterial to pass through the coating or impregnating mixture. After sucha coating or impregnation has been effected the support is dried at atemperature not exceeding that at which substantial cross-linking of theresin occurs, preferably below C. The support is then printed with thedesired information-bearing marking or pat tern and the printed labelsor label strip is then dried again at a temperature below that at whichsubstantial cross-linking occurs, generally below 100 C.

Labels produced with such resin systems are applied under heat andpressure in a suitable heat sealing press at a temperature in excess ofthe softening temperature of the resin used. At these temperatures rapidcrosslinking of the resin occurs with the formation of a permanent bondto the article being marked, the bond and the label itself then beingcapable of withstanding repeated laundering and dry chemical cleaningoperations.

The following examples illustrate typical methods of producingheat-sealable labels according to the present invention and as shown onthe drawing.

EXAMPLE I A 40 gm. per sq. m. high wet strength paper of high absorbencywas impregnated with gm. per sq. in. (dry weight) of a mixture selectedfrom Table I or Table II.

A coating of 25 gm. per sq. m. was applied to one side only, using thesame mixture selected for impregnation and the coating dried, at atemperature below .that at which the resin cross-links rapidly, i.e.,below 100 C.

A design was then printed repetitively, using an ink selected from TableIII, Nos. 1 to 13 using the resin selected for impregnation.

Drying was carried out at a temperature below that it which the resincross-links rapidly, i.e., below 100 C. Conveniently the paper ismanipulated in the form )f a continuous strip which is formed intorolls. Labels were cut from the rolls prepared as above and were :estedby being applied to a range of textile fabrics in- :luding cotton,linen, nylon, polyester, glass cloth, sing a heat-sealing press givingapplication conditions )f 200C, 4 seconds, 40 lbs. per sq. in.

The fabrics with applied labels were then subjected Lo many cycles ofthe appropriate laundry treatment 1nd showed good resistance up to 30-50successive vreatments.

Further tests were carried out applying labels onto vool, cellulosediacetate and acrylic fabrics at 180 C. .econds, lbs. per sq. in.,followed by hand washing )r dry-cleaning.

These labels were still legible after 30-50 treatments.

EXAMPLE II An 80 gm. per sq. m. closely woven cotton fabric was :oatedsubstantially on one side only, with 50 gm. per q. m of a mixtureselected from Table I or Table II.

It was then printed repetitively on the opposite side lsing one or moreinks selected from Table III. Nos. 1 o 13 without regard for resin type.

Labels prepared in this way were tested as in Examile I and were foundto be legible after the fabric was worn out.

EXAMPLE III A 50 gm. per sq. m. viscose non-woven fabric was imregnatedwith 20 gm. per sq. m. of a mixture selected rom Table I or Table I]followed by coating with a sim- .ar mixture to about 30 gm. per sq. m.on one side only.

A repetitive design was then printed on the uncoated ide using inksfreely selected from Table III, Nos. 1 to 4. The printed side was thencoated with a further 15 m. per sq. m. of the mixture used forimpregnation and eating.

Labels cut from these rolls were tested in a similar vay to Example I,and were found to be legible when he fabric was worn out.

EXAMPLE IV A 45 gm. per sq. m. high wet strength, highly absorent paper,comprising 10% of carbon black, was irnregnated and coated as Example I.This was then cut [to sheets of a suitable size for screen printing.

It was then printed with an ink selected from Table 1, Nos. 1 to 13, butof the same resin type used for impregnation, with industrial ethanolreplaced by nbutanol.

It was tested in the same way as Example I, with similar results.

EXAMPLE V A 35 gm. per sq. m. high wet strength, highly absorbent paper,was impregnated with 18 gm. per sq. m. of an ink selected from TableIII, Nos. 1 to 13. It was then coated with 30 gm. per sq. m. of amixture selected from Table I or Table II, using the same resin type.

Printing was carried out using a contrasting colour selected from TableIII, Nos. 1 to 13.

It was tested in the same way as Example I with similar results.

EXAMPLE VI a. A gm. per sq. m. high wet strength paper of low absorbencywas coated on one side only with 50 gm. per sq. m. of a mixture selectedfrom Table I or Table II.

It was then printed on the other side using an ink freely selected fromTable III, Nos. 1 to 13.

These labels were intended for use by a linen hire organisation and areintended to carry in addition to the printed information individualmarkings. Cut labels were applied on to cotton or linen overalls at 250C., 4 seconds, 60 lbs. per sq. m. in., and after application additionalinformation was inserted such as the name of the lessee, date ofcontract, etc., by means of a laundry marking ball point pen (assupplied by Scripto Ltd). Labels formed in this way were found towithstand about 50 laundry operations.

b. By applying a transparent, unprinted transfer layer applied from atemporary support, as a protective covering, preferably using the samecoating solutions or dispersions under the same conditions, the labelcould be made to last throughout the useful life of the gar ment.

Such transfer layer was prepared by coating a 60 micron film ofcellulose triacetate with 15 gm. per sq. m. of a mixture selected fromTable I or Table II and then dried. The dried coating was placed incontact with the label and subjected to heat the pressure under the sameconditions as the labels, and the support film peeled off or allowed todetach itself.

EXAMPLE VII A 38 micron film of regenerated cellulose was printed withan ink freely selected from Table III, Nos. 1 to 13 and then coated onboth sides with 20 gm. per sq. m. of a mixture selected from Table I orTable II.

It was tested in the same way as Example I and found to offer similarresistance to repeated laundering.

EXAMPLE VIII Labels were prepared in a similar way to Example I using acoating solution selected from Table l with three parts of a plasticiserselected from Table IV.

EXAMPLE IX Labels were prepared in a similar way to Example I, using acoating mixture selected from Table II with 10 parts per 100 parts ofresin dispersion of a plasticiser selected from Table V.

It will be understood that labels according to the present invention maybe economically produced since an inexpensive class of support materialmay be used, typically a soft and absorbent paper, which is coated orimpregnated with the resin solution or dispersion in fluent form, andthen dried. Because of the absence of a temporary support theapplication of heat from the presser means used for applying it to thearticle to be marked is operative rapidly, permitting the applicationand bonding of the label to the article to be effected in a period ofnot more than 7 seconds at most in practical cases. Because the printedmarking on the label is visible at all times, control of the printingduring production of the labels is facilitated, and this easy visibilityis also of advantage in facilitating the correct application of thelabel to the article to be marked. All these factors contribute inproviding a low cost procedure for producing marking elements havinginformationbearing markings printed thereon. The resin component ofthese marking elements is converted into an insoluble, abrasionandwash-resistant compound by heat and pressure. The printing ink itself iseither converted into a similar compound or the printing ink isprotected on each side by continuous layers of such cured compounds. Theresulting marking elements are highly resistant to influences operativethroughout the life of the article being marked, including resistance towear and resistance to cleaning operations such as cleaning solvents,without substantial degradation of the information carried by themarking element.

In some cases it may be desired to improve the appearance of the labelsafter application to the article by utilising a presser member operativeon the exposed surface of the transfer which embodies an engravedsurface pattern or grain which may give a characteristic appearance, forexample, a natural textile appearance, to the label while in position onthe article.

What I claim is:

l. A marking element permanently attachable by heat and pressure to asurface to be marked, comprising a paper-like flexible permanent supportsheet completely impregnated with a heat curing film-forming resinsystem, a further coating of a heat curing filmforming resin system onone side of said support and an information-bearing marking imprinted onthe other side of said support, said marking also including a heatcuring, film-forming resin system and said film-forming resin systemsbeing selected from the group consisting of soluble polyamides, solublecopolyamides, and cross-linking acrylic resins and including alkylol oralkoxy alkyl groups under acid conditions for conversion of said resinsystem under said heat and pressure into an inert, insoluble andabrasion-resisting substance in situ on the surface to'be marked.

2. A marking element according to claim 1, wherein theinformation-bearing marking is produced by means of a printing inkincluding a cross-linkable resin system. I: 3. A marking elementaccording to claim 1,

.wherein the information-bearing marking is protected by a transparentprotective layer on the exposed surface.

4. A marking element according to claim 1, wherein the resin systemconsists of a soluble polyamide in the presence of alkylol or alkoxyalkyl groups such that at said temperature above the softeningtemperature cross-linking of the polyamide occurs with the formation ofan inert and insoluble compound bonding the label to the surface to bemarked.

5. A marking element according to claim 4, wherein the soluble polyamideconsists of a methoxy methyl de rivative of a polyamide.

6. A marking element according to claim 4, wherein the resin systemincludes a soluble copolyamide in the presence of a cross-linking agentcontaining alkoxy alkyl groups.

7. A marking element according to claim 6 wherein the cross-linkingagent is a formaldehyde'resin containing alkoxy alkyl groups.

8. A marking element according to claim 1, wherein the resin systemincludes a cross-linking acrylic resin.

9, A marking element permanently attachable by heat and pressure to asurface to be marked, comprising a paper-like flexible permanent supportsheet completely impregnated with a heat curing film-forming resinsystem, a further coating of a heat curing film-forming resin system onone side of said support and an informationbearing marking imprinted onthe other side of said support, said information-bearing marking beingprotected by a transparent protective layer consisting of a filmformingresin system, each of said film-forming resin systems being selectedfrom the group consisting of soluble polyamides, soluble copolyamides,and cross-linking acrylic resins, and also including alkylol or alkoxyalkyl groups under acid conditions for convertion of said resin systemunder said heat and pressure into an inert, insoluble andabrasion-resisting substance in situ on the surface to be marked.

10. A marking element according to claim I, wherein saidinformation-bearing marking is protected by a transparent protectivelayer consisting of a film-forming resin system selected from the groupconsisting of soluble polyamides, soluble copolyamides, andcross-linking acrylic resins and including alkylol or alkoxy alkylgroups under acid conditions for conversion of said resin system undersaid heat and pressure into an inert, insoluble and abrasion-resistingsubstance in situ on the surface to be marked.

1. A MARKING ELEMENT PERMANENTLY ATTACHABLE BY HEAT AND PRESSURE TO ASURFACE TO BE MARKE, COMPRISING A PAPER-LIKE FLEXIBLE PERMANENT SUPPORTSHEET COMPLETELY IMPREGNATED WITH A HEAT CURING FILM-FORMING RESINSYSTEM, A FURTHER COATING OF A HEAT CURING FILM-FORMING RESIN SYSTEM ONONE SIDE OF SAID SUPPORT AND AN INFORMATION-BEARING MARKING IMPRINTED ONTHE OTHER SIDE OF SAID SUPPORT, SAID MARKING ALSO INCLUDING A HEATCURING, FILM-FORMING RESIN SYSTEM AND SAID FILM-FORMING RESIN SYSTEMSBEING SELECTED FROM THE GROUP CONSISTING OF SOLUBLE POLYAMIDES, SOLUBLECOPOLYAMIDES, AND CROSS-LINKING ACRYLIC RESINS AND INCLUDING ALKYLOL ORALKOXY ALKYL GROUPS UNDER ACID CONDITIONS FOR CONVERSION OF SAID RESINSYSTEM UNDER SAID HEAT AND PRESSURE INTO AN INERT, INSOLUBLE ANDABRASION-RESISTIN SUBSTANCE IN SITU ON THE SURFACE TO BE MARKED.
 2. Amarking element according to claim 1, wherein the information-bearingmarking is produced by means of a printing ink including across-linkable resin system.
 4. A marking element according to claim 1,wherein the resin system consists of a soluble polyamide in the presenceof alkylol or alkoxy alkyl groups such that at said temperature abovethe softening temperature cross-linking of the polyamide occurs with theformation of an inert and insoluble compound bonding the label to thesurface to be marked.
 5. A marking element according to claim 4, whereinthe soluble polyamide consists of a methoxy methyl derivative of apolyamide.
 6. A marking element according to claim 4, wherein the resinsystem includes a soluble copolyamide in the presence of a cross-linkingagent containing alkoxy alkyl groups.
 7. A marking element according toclaim 6 wherein the cross-linking agent is a formaldehyde resincontaining alkoxy alkyl groups.
 8. A marking element according to claim1, wherein the resin system includes a cross-linking acrylic resin.
 9. AMARKING ELEMENT PERMANENTLY ATTACHABLE BY HEAT AND PRESSURE TO A SURFACETO BE MARKED, COMPRISING A PAPER-LIKE FLEXIBLE PERMANENT SUPPORT SHEETCOMPLETELY IMPREGNATED WITH A HEAR CURING FILM-FORMING RESIN SYSTEM, AFURTHER COATING OF A HEAT CURING FILM-FORMING RESIN SYSTEM ON ONE SIDEOF SAID SUPPORT AND AN INFORMATION-BEARING MARKING IMPRINTED ON THEOTHER SIDE OF SAID SUPPORT, SAID INFORMATION-BEARING MARKING BEINGPROTECTED BY A TRANSPARENT PROTECTIVE LAYER CONSISTING OF A FILMFORMINGRESIN SYSTEM, EACH OF SAID FILM-FORMING RESIN SYSTEMS BEING SELECTEDFROM THE GROUP CONSISTING OF SOLUBLE POLYAMIDES, SOLUBLE COPOLYAMIDES,AND CROSS-LINKING ACRYLIC RESINS, AND ALSO INCLUDING ALKYLOL OR ALKOXYALKYL GROUPS UNDER ACID CNDITIONS FOR CONVERTION OF SAID RESIN SYSTEMUNDER SAID HEAT AND PRESSURE INTO AN INERT, INSOLUBLE ANDADRASION-RESISTING SUBSTANCE IN SITU ON THE SURFACE TO BE MARKED.
 10. Amarking element according to claim 1, wherein said information-bearingmarking is protected by a transparent protective layer consisting of afilm-forming resin system selected from the group consisting of solublepolyamides, soluble copolyamides, and cross-linking acrylic resins andincluding alkylol or alkoxy alkyl groups under acid conditions forconversion of said resin system under said heat and pressure into aninert, insoluble and abrasion-resisting substance in situ on the surfaceto be marked.